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Unformatted text preview: If I know the focal length in meters, the power of the lens is 1/f , in units of diopters. This can be positive or negative. Simple magnifier (i.e. a magnifying glass): Theres not much to this section that you havent already learned in chapter 23. The only new concept here is that of angular magnification. What you have to realize is that when you look at an object, you see that it has a certain size, but in actual fact, your eye just sees that the object is a certain angle wide (because your eye only knows direction). Look at figure 25.5 on page 787 if this last sentence confuses you. Clearly, if I change the apparent size of an object, the angle it takes up when you look at it will change. So, the angular magnification is given by: m = / , where is the angle spanned by the image and is the angle spanned by the object. THE END. GOOD LUCK!...
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- Spring '08